In March 1989, first instar Toxorhynchites moctezuma larvae were introduced into all potential Aedes aegypti oviposition sites (n = 214) that contained water in the village of Clifton on Union Island in St. Vincent and The Grenadines. One month after this introduction, the mean number of adult Ae. aegypti collected with a backpack aspirator in houses in Clifton dropped significantly. Sixty-four percent fewer males and 80% fewer females were collected after introduction of the predator. In the untreated village of Ashton, the overall drop was 24%, with males showing an increase of 27% and females a drop of 55%. The average wing length of females collected in Clifton increased slightly, whereas it remained the same in Ashton.